yusuf chemistry

8/8/2019 Yusuf Chemistry

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Introductory Chemistry 1

Prepared by Prof. Paul M. Shiundu

with Dahir Mohamed Yusuf

African Virtual universityUniversit Virtuelle AfricaineUniversidade Virtual Africana


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African Virtual University

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This document is published under the conditions of the Creative Commons

http://en.wikipedia.org/wiki/Creative_Commons

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License (abbreviated cc-by), Version 2.5.


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I. Chemistry1:IntroductoryChemistry1__________________________3

II. PrerequisiteCourseorKnowledge_____________________________3

III. Time____________________________________________________3

IV. Materials_________________________________________________4

V. ModuleRationale __________________________________________4

VI. Content__________________________________________________4

6.1 Overview____________________________________________4

6.2 Outline_____________________________________________5

6.3 Graphicorganizer_____________________________________6

VII. GeneralObjective(s)________________________________________7

VIII. SpecificLearningObjectives__________________________________7

IX Pre-assessment __________________________________________11

X. KeyConcepts(Glossary)____________________________________17

XI. CompulsoryReadings______________________________________18

XII. CompulsoryResources_____________________________________20

XIII. UsefulLinks _____________________________________________23

XIV. TeachingandLearningActivities______________________________30

XV. SynthesisOfTheModule ___________________________________86XVI. SummativeEvaluation______________________________________87

XVII.References ______________________________________________91

XVIII.StudentRecords_________________________________________92

XIX.FileStructure ____________________________________________93

Table of ConTenTs


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i. Chmitry 1: Itrductry Chmitry 1

by Dahir Mohamed Yusuf, Amoud University

II. Prrquiit Cur r Kwdg

Entry requirements for undergraduate university studies in science. Students

are expected to have done chemistry as a subject in high school as well as Ma-thematics.

III. Tim

A total of 120 hours is required to complete this module and the allocation is as

follows:

Unit Topic Approximateno.ofhours

1 Matter and measurements 30 hours2 Atomic structure and periodicity 30 hours

3 Molecules and compounds 30 hours

4 Chemical reactions and stoichiometry 30 hours

IV. Mtri

To successfully complete the learning activities in this module you will require

Internet-connectivity to enable you to access and /or use the following tools and

resources:

CD-ROMs;

Internet-based:-

Computer aided instruction (CAI)

Computer-based assessment (CBA)

Multimedia delivery (including video conferencing)

e-Library and data base utilization

Integrated learning environment

Interactive discussions/chat sessions; and

Recommended textbooks and other reference materials


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V. Mdu Rti

This is an introductory module aimed at helping you to upgrade and consolidate

your knowledge of some of the fundamentals of chemistry. To be successful, you

must master concepts that form the building blocks of chemistry as well as acquire

mathematical skills necessary to solve problems in this quantitative science. Che-

mistry, like driving a car, uses a language and skills of its own. Without a rm

foundation in these fundamentals, a true understanding of chemistry is impossible.

This module in part, begins to construct that foundation by introducing some keyaspects of the chemists view of matter. The module will enable the learner to

learn some of the language of chemistry and develop an image of the physical

world that will help you think like a Chemist.

VI. Ctt

6.1Overview

This module covers introductory topics that are fundamental to understanding

the subject of chemistry. In this module, we shall examine the structure of the

smallest part of an element known as the atom (the building blocks of matter) and

associated atomic models. The focus will be on the thought process involved in

the development of the periodic table and its use in explaining the structure and

properties of elements in groups and periods. Both microscopic (in which

matter is regarded as a collection of atoms and molecules) and macroscopic (asso-

ciated with the bulk properties of matter) views of matter will be considered. The

underlying principles that govern structures and shapes of simple molecules and

ions will be covered as well as the nomenclature for writing formula for binary

inorganic compounds, cations and anions. In addition, a review of the concepts

behinds interpretation and balancing of chemical equations, stoichiometric cal-

culations involving quantitative relations in chemical reactions, calculations of

percent composition by mass and derivation of molecular formula from experi-

mental data will also be made.


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6.2Outline

UnitI:Matterandmeasurements(30Hours)

- Classications of matter

- Physical and chemical properties of matter

- Matter and Energy

- Measurement

UnitII:AtomicStructureandPeriodicity(30Hours)

- The Atomic theory

- Development of the atomic theory and models

- Atomic Mass, Mass Number, Isotopes

- Writing Electronic Congurations

- The Periodic Table

UnitIII:Bonding,MoleculesandPeriodicity(30Hours)

- The ionic and covalent bonds

- Intermolecular forces

- Formal charge and Lewis Structure

- Molecules and ions

UnitIV:ChemicalReactionsandStoichiometry(30Hours)

- Percent composition of compounds

- Experimental determination of empirical and molecular formula

- Writing and balancing of chemical equations

- Stoichiometery and calculations

- Use of the mole concept in stoichiometric calculations


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6.3GraphicOrganizer(canbedrawnmanually)


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VII. Gr ojctiv()

Thegeneralobjectivesofthismodulearefive-fold:

To classify matter into types so as to make manageable the wealth of

information about matter.

To distinguish between matter and energy.

To begin to classify elements in a systematic manner.

To use the units of a measurement to do calculations involving that measu-

rement.

To use the laws of chemical combination to understanding chemical

equations, balancing them and doing stoichiometriccalculations.

VIII. spcic lrig ojctiv(Itructi ojctiv)

UnitI:MatterandMeasurement

At the end of the unit the student should be able to:

- Identify and explain physical and chemical properties

- Identify what distinguishes between solids, liquids and gases from each

other

- Distinguish between matter and energy

- Use SI units to make scientic calculations and

- Determine uncertainties and error levels in chemical experiments

UnitII:AtomicStructureandPeriodicity

At the end of this unit the learner should be able to:

- Discuss the development of the atomic theory and models

and write electronic congurations of atoms.

- Understand the modern atomic theory and describe the structure of the

atom.

- Write electronic conguration of atoms.

- Dene atomic and mass number and carry out related calculations.

- Describe the thought process involved in the development of the periodic

table.- Use the periodic table to explain the structure and the properties of ele-

ments in groups and periods.


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UnitIII:Bonding,MoleculesandCompounds


- Distinguish between ionic and covalent bonding.

- Describe and explain the criteria for determining types of intermolecular

bonding.

- Use IUPAC nomenclature to name and write formula for binary inorganic

compounds, cations and anions.

- Explain and predict chemical bonding, structure and geometrics of simple

molecules and ions.

- Describe and apply the Lewis theory in making Lewis structure of binary

compounds.

UnitIV:ChemicalReactionsandStoichiometry


- Calculate percent composition by mass and derive chemical formulae

from experimental data.

- Balance and interpret chemical equations in terms of reactions and pro-ducts.

- Dene and use the idea of the mole to perform stoichiometric calculations

involving quantitative relations in chemical reactions.

UnitNumber

UNITIMatterandMeasurement

LearningObjective(s)

- Identify and explain the differen-

ces between solids, liquids and

gases.

- Identify and explain differences

between physical and chemical

properties of materials.

- Distinguish between physical and

chemical changes.

- Discuss the differences between

matter and energy.

- Use the SI units of measurements

to carry out relevant calculations

associated with that particular

measurement.- Determine uncertainties and error

levels in chemical experiments.


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UNITIIAtomicStructureandPeriodicity

UNITIIIBonding,MoleculesandCompounds

- Explain and distinguish between

the various atomic theories.

- Explain the modern atomic theory

and structure and write electronic

congurations of atoms.

- Write the nuclear symbol of an

element.

- Dene atomic mass, mass number

and isotopes and carry out relatedcalculations.

- Explain and discuss the thought

process involved in the develop-

ment of the periodic table.

- Explain the structure and proper-

ties of elements in groups and

periods using the periodic table.

- Describe the two fundamental

types of chemical bonding (i.e.,

ionic and covalent).

- Know and compare properties of

ionic compounds and covalent

compounds.

- Know and use the IUPAC chemi-

cal nomenclature for the syste-

matic naming of chemical com-

pounds.

- Classify compounds as ionic or

covalent.

- Dene and distinguish betweenempirical formulas, molecular

formulas, and structural formulas

for compounds.

- Dene, calculate and relate formu-

la weights and molecular weights.

- Use the IUPAC chemical nomen-

clature to name and write chemi-

cal formulas for binary inorganic

compounds (covalent or ionic),

simple ionic compounds (cations

and anions).


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African Virtual University 0

UNITIVChemicalReactionsandStoichiometry

- Explain the mole concept, and

convert between grams, moles,

and atoms and molecules.

- Determine mass percent composi-

tion of a sample from experimen-

tal data.

- Understand the concept of basic

stoichiometry and related calcula-

tions.- Determine mass percent com-

position of a compound from its

formula.

- Determine empirical formula of a

compound from its mass percent

composition.

- Write balanced chemical equa-

tions from descriptions of chemi-

cal changes.

- Interpret chemical equations in

terms of reactants and products.

- Classify chemical reactions as

say, precipitation, neutralization,

combustion, decomposition, etc.

- Write formation and combustion

reactions for given compounds.


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IX. Pr-mt

Title of Pre-assessment :

Rationale:An atom is the smallest part of an element and constitute the building

blocks of matter as we know it since matter is regarded as a collection of atoms

and molecules. As the most basic unit that determines the structure and properties

of elements, the learning of chemistry as a subject begins with atoms. For thisreason, a set of pre-assessment questions are provided below which are meant

to help you assess your previous understanding of this basic unit of matter and

associated concepts. You will nd some questions rather unfamiliar but these are

meant to give you some idea of what to expect in this module.

Questions

1. An atom is

a) The smallest particle in the nucleus

b) The major component of an acid.

c) The basic building block of matter

d) A particle not larger than the proton.

2. The nucleus of an atom contains

a) Clouds of gases and many other substances.

b) Neutrons and protons.

c) Electrons and protons.

d) Protons and similar other particles.

3. If I meter =3.28 ft , then 50 meters will be

a) 95 ft.

b) 164 ft.

c) 210.53 ft.

d) 181.5 ft.

4. The mass of an atom is expressed in

a) Pounds per volume.

b) Atomic mass units.

c) Volume per kilogram.

d) None of the above.


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5. Matter is anything that

a) Occupies space and is solid only.

b) Occupies a space only

c) Occupies a space and has a mass.

d) Occupies a space and is not liquid.

6. Mixtures are always

a) Heterogeneous

b) Heterogeneous in solution form

c) inseparable

d) Both heterogeneous and homogeneous.

7. Compounds can be

a) Decomposed by chemical changes.

b) Heterogeneous substances

c) Only solid substances.

d) Both solid and liquid substances.

8. Electrons are the

a) Only particles seen in the nucleous of atoms.

b) The particles that determine the mass of an atom

c) Particles that are found in the shells of the atom.


9. The atomic number

a) Determines the type of atom.

b) Is similar to the mass number.

c) Is equal to neutrons plus protons.

d) Is greater than the mass number.

10. The bond between atoms that share electrons

a) Is called sigma bond.

b) Is called a covalent bond.

c) Is an ionic bond.

d) Is both ionic and covalent bond.


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11. A single bond results when

a) Two pairs of electrons are shared between two atoms.

b) Two or more pairs of electrons are shared.

c) Two ionic bonds are joined together.

d) Two electrons are shared between two atoms.

12. The measure of the ability of an atom to attract a pair of electrons

a) Is called simple attraction.

b) Is called electro negativity.

c) Is called ionic contraction.

d) All are correct.

13. Ionic bonds are often

a) Stronger than normal bonds.

b) Weaker than normal bonds.

c) Stronger than covalent bonds.

d) Weaker than covalent bonds.

14. If sodium hydroxide is added to hydrochloric acid

a) The product is chlorine gas.

b) The product is chlorine and hydrogen gases.

c) The product would be sodium chloride only.

d) The product would be sodium chloride and water.

15. An orbital is characterized by

a) The principle quantum number.

b) The azimuthal quantum number.

c) The magnetic quantum number.

d) a, b, and c

16. Elements in which the s and p orbitals in the outer shell are completely lled

are:

a) All solid elements.

b) Both liquid and solid elements.

c) Solid, liquid, and gasd) Noble gases.


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17. A sodium atom can easily form an ionic bond with

a) A carbon atom.

b) A neon atom.

c) A lead atom.

d) A chlorine atom.

18. Hydrogen readily forms a covalent bond with

a) Atoms of all elements.

b) The halogens.

c) Atoms in group III A.


19. Gases are

a) Substances that take the shape of their containers.

b) Substances that take the volume of their containers.

c) Not compressible.

d) A and b

20. Select the correct symbol of calcium

a) C

b) Ca

c) CA

d) ca


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Title of Pre-assessment : _____________________________

AnswerKey

1. C

2. B

3. B

4. B

5. C

6. D

7. A

8. C

9. A

10. B

11. D

12. B

13. C

14. D

15. E

16. D

17. D

18. B

19. D

20. B

Notes to the student:

If you get 10 items or more correct you can consider that you are doing ne.

However, if you get less than 8 items correct then you need to put in extra effort

to perform well in this module.


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PedagogicalCommentsForLearners

Important Tips:

You will be able to appreciate why various substances behave the way

they do by understanding the theory and structure of atoms. This is quite

fundamental in conceptualizing the very existence of inter- and intra bon-

ding between the components that make up an element and molecules,

respectively.

Bohrs theory is of fundamental importance in understanding the beha-vior of matter in general and need to be mastered properly. It forms the

foundation of this module.


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X. Ky Ccpt (Gry)

A pure substance: A substance with a denite chemical composition.

Atom: the smallest particle of an element that retains the identify and properties

of the element and can take part in a chemical change.

Atomic number (symbol Z): the number of protons in the nucleus of each

atom.

Compound: a substance that is formed when two or more elements combine

chemically to form a substance with completely different properties.

Electron Conguration: the arrangement of electrons in the orbitals of an

atom.

Element: a substance that cannot be separated chemically into any simpler subs-

tances, e.g., Oxygen O2; chlorine, Cl

2; carbon, C; and copper metal, Cu.

Isotopes: different varieties of an element, identical in chemical properties

but differing slightly in atomic weight, i.e., If two atoms of an element have

the same number of protons, but different numbers of neutrons, they are called

ISOTOPES.

Mass number (symbol A): the total number of protons and neutrons in the

nucleus of each atom.

Mole of a substance:the amount of substance that contains as many elementary

entities (e.g, electrons, atoms, molecules) as there are atoms in exactly 12 grams

(0.012kg) the carbon-12 isotope.

Molecule: the smallest mass of an element or compound capable of existing alone

and possessing the properties of that element or compound.

Periodic Law: states that the properties of the elements are periodic functions

of their atomic numbers.

Periodic Table: the arrangement of atoms in increasing order of their atomic

numbers that puts atoms with similar properties in vertical columns.

Chemical Reaction: A chemical change which may be simple combination as

in the case of two elements.


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XI. Cmpury Rdig

Reading#1

Complete reference: See PDF le named Bishop_Book_1_eBook.pdf

Abstract : This is a 29-page Chapter of a book entitled An Introduction toChemistry; an Openware Source material. The chapter comprises of 5 relevant

subsections namely; What is Chemistry and What can Chemistry do for you?;

Suggestions for studying chemistry; The scientic method; Measurement and

Units; and Reporting values from measurements.

Rationale: This chapter is an excellent reading material for people wishing to

develop interest in learning and teaching chemistry as a subject. The rst three

subsections provide general but important information for developing interest

in the subject of chemistry. The latter two subsections are directly relevant to

Unit 1 of this module, which deals with Matter and Measurements. Within

this chapter, you will nd information on the origin of International System of

Measurements (SI Units) and its relevance. The chapter illustrates the use ofthe International System of Measurements base units and their abbreviations to

describe length, mass, time, temperature, and volume. The end of this Chapter

contains a glossary section from where important denitions can be found. In

addition, practice questions that are relevant to the topic are also provided.

Reading#2


Abstract :This is a 35-page Chapter 2 of a book entitled The Structure of Matter

and the Chemical Elements; an Openware Source material. The chapter is made

of 5 subsections whose corresponding subtitles are; Solids, Liquids, and Gases;

The Chemical Elements; The Periodic Table of the Elements; The Structure of

the Elements; and Common Elements. All these subtopics are very relevant to

some of the contents of this module.

Rationale: This chapter begins a journey that will lead you to understanding of

chemistry. It provides you with the basic knowledge of the chemical principles

and underlying facts related to chemistry. The chapter will enable the learner to

learn some of the language of chemistry and develop an image of the physical

world that will help the learner think like a Chemist.


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Reading#3


Abstract : This is a 55-page Chapter 3 of a book entitled Chemical Compounds;

an Openware Source material. The chapter comprises of 5 subsections whose

corresponding subtitles are; Classication of Matter; Compounds and Chemical

Bonds; Molecular Compounds; Naming Binary Covalent Compounds; and Ionic

Compounds.

Rationale: Most of the substances that we see around us are consist of two or

more elements that have combined chemically to form more complex substances

called compounds. In this chapter, you will learn to (a) dene the terms mixture

and compound more precisely, (b) distinguish between the terms elements, com-

pounds, and mixtures, (b) describe how elements combine to form compounds,

(c) construct systematic names for some chemical compounds, and (d) describe

the charateristics of certain kinds of chemical compounds. The chapter will also

expand your ability to visualize the basic structures of matter.

Reading#4


Abstract : This is a 33-page Chapter 4 of a book entitled An Introduction to

Chemical Reactions; an Openware Source material. The chapter comprises of 2

subsections whose corresponding subtitles are; Chemical Reactions and Chemical

Equations; and Solubility of Ionic Compounds and Precipitation Reactions.

Rationale: Once one understands the basic structural differences between different

kinds of substances, the next important step is to learn how chemical changes

takes place as one subtsnce is converted into the other. Such chemical changes

are typically the concern of a chemist. Chemists often want to know, if anything

happens when one substance encounters another. Whether the substances change

and if so, why and how? In this chapter, the learner will nd out about a chemi-cal change that occurs when, say a solid dissolves in water, etc. These kind of

changes can be described with chemical equations. This chapter begins with a

discussion of how to interprete and write chemical equations.


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XII. Cmpury Rurc

Resource#1

Complete reference: The relevant titles of the simulations are: Simulated hy-

drogen and helium atoms and Hydrogen Ion Simulation. The corresponding

sites are:

http://www.visionlearning.com/library/x_linker.php?moid=2494 & http://www.

visionlearning.com/library/x_linker.php?moid=2141, respectively.

Abstract : Atoms are electrically neutral because the number of protons (+ char-

ges) is equal to the number of electrons (- charges) and thus the two cancel out.

Ions on the other hand are charged (+ or charges). As the atom gets larger, the

number of protons increases, and so does the number of electrons (in the neutral

state of the atom). The rst illustration linked above compares the two simplest

atoms, hydrogen and helium. The second is an the animation that shows a positive

hydrogen ion (which has lost an electron) and a negative hydrogen ion (which

has gained an extra electron). The electron charge on the ion is always writtenas a superscript after the atoms symbol, as seen in the animation.

Rationale: We now know that atoms are extremely small. One hydrogen atom(the

smallest atom known) is approximately 5 x 10-8 mm in diameter. To put that in

perspective, it would take almost 20 million hydrogen atoms to make a line as

long as this dash -. Most of the space taken up by an atom is actually empty

because the electron spins at a very far distance from the nucleus. For example,

if we were to draw a hydrogen atom to scale and used a 1-cm proton (about the

size of this picture - ), the atoms electron would spin at a distance of ~0.5

km from the nucleus. Now, this is generally, difcult to visualize and concep-

tualize the very existence of an atom with its subatomic particles. As much asthe learner will be able to read material pertaining to the atom, it is bound to

be difcult to picture this supposedly small entity that all matter is made of.

This simulated illustration, is meant to show the learner what an atom and an ion

looks like, the positioning and movement of the electron(s) (where applicable)

with respect to the nucleus and compares the two simplest atoms of hydrogen and

helium. It is hoped that with these illustrations, the learner will be better placed

in conceptualizing the existence of both an atom and an ion.


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Resource#2

Complete reference: The relevant titles of the simulations are: Bohrs Atom:

Quantum Behavior in Hydrogen. The corresponding site is:

Javascript:WinOpen(/library/ash_viewer.php?oid=1347&mid=51,VLFlash

,770,660);

Abstract : Under Bohrs theory, an electrons energy levels (also called electron

shells) can be imagined as concentric circles around the nucleus. Normally, elec-

trons exist in the ground, meaning they occupy the lowest energy level possible

(the electron shell closest to the nucleus). When an electron is excited by adding

energy to an atom (for example, when it is heated), the electron will absorb energy,

jump to a higher energy level, and spin in the higher energy level. After a

short time, this electron will spontaneously fall back to a lower energy level,

giving off a quantum of light energy. Key to Bohrs theory was the fact that the

electron could only jump and fall to precise energy levels, thus emitting a

limited spectrum of light. The animation linked above simulates this process in

a hydrogen atom. Concept simulation - Reenacts electrons jump and fall

to precise energy levels in a hydrogen atom. (Flash required)

Rationale: According to Bohr, the line spectra phenomenon showed that atoms

could not emit energy continuously, but only in very precise quantities (he

described the energy emitted as quantized). Because the emitted light was due

to the movement of electrons, Bohr suggested that electrons could not move

continuously in the atom (as Rutherford had suggested) but only in precise steps.

Bohr hypothesized that electrons occupy specic energy levels. When an atom

is excited, such as during heating, electrons can jump to higher levels. When the

electrons fall back to lower energy levels, precise quanta of energy are released

as specic wavelengths (lines) of light. This animation affords the learner an

opportunity to see existence of discrete lines and the origin of light emission upon

excitation of an electron.

Resource#3

Complete reference: The relevant titles of the simulations are: The Lithium

atom and Atomic structure animation table. The latter provides further details

through a table linked which shows the electron congurations of the rst eleven

elements. The corresponding sites are:

http://www.visionlearning.com/library/x_linker.php?moid=2495 & http://www.

visionlearning.com/library/x_linker.php?moid=2496, respectively.

Abstract:Not only did Bohr predict that electrons would occupy specic energy

levels, he also predicted that those levels had limits to the number of electrons

each could hold. Under Bohrs theory, the maximum capacity of the rst (orinnermost) electron shell is two electrons. For any element with more than two


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electrons, the extra electrons will reside in additional electron shells. For exam-

ple, in the ground state conguration of lithium (which has three electrons) two

electrons occupy the rst shell and one electron occupies the second shell. This

is illustrated in the animation linked below.

Rationale: The concept of lling electron shells with electrons is just as abs -

tract as conceptualizing the existence of at atom. This animation for the lithium

atom would help the learner appreciate these phenomena and is valuable to the

learner.


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XIII. Uu lik

UsefulLink#1

Title: Matter: Atoms from Democritus to Dalton, Visionlearning Vol. CHE-1

(1), 2003.

URL :http://www.visionlearning.com/library/module_viewer.php?mid=49

Screen capture :

Description: This is an Open Source Visionlearning Volume CHE-1(1) book

material by Anthony Carpi, Ph.D. entitled Matter: Atoms from Democritus to

Dalton. Within this site, you will be linked to other useful sites.

Rationale: This is a useful link as it provides the learner with an important

chronology of developments from early theories governing matter to the modern

understanding of matter as we know it today. In here, the origin of the Law of

conservation of mass is articulated. Also, through this site you will have access

to Daltons Playhouse: an interactive, virtual set of experiments that allow youto recreate classic experiments from the 19th century.

UsefulLink#2

Title : Virtual Chemistry Experiments and Exercises

URL : http://www.chm.davidson.edu/ChemistryApplets/index.html

Screen capture :

Description: This is an open source site that allows the learner to carry out virtual

experiments and exercise relevant to some sections of this module. Among the

signicant topics include Atomic Struture and Chemical Bonding.

Rationale: This is a must-see site that enables the learner to carry out virtual

chemistry experiments and exercises. The topics of signicance to this module

includes Atomic Structure and Chemical bonding. Under the former, the

learner will exposed to virtual chemistry experiments and exercises that deal

with atomic and hybrid orbitals. The latter will have material on hybrid and

molecular orbitals. In both situations, the Virtual Reality Modeling Language

(VRML) will be used to display three-dimensional images of molecular structure

and orbitals. Through the choice of the relevant links, the learner will be able to

see (a) the isosurfaces of various atomic orbitals and some hybrid orbitals and

Isosurfaces, radial distribution plots, and electron density plots of various atomic

orbitals displayed. Virtual experiments showing shapes and orientation of s, p,

and d orbitals are displayed. The signicance of orbital overlap in forming a


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chemical bond is explained. Sigma, pi, and delta bonding interactions are also

explained. The overlap of two s orbitals is illustrated among other important

aspects of these topics.

UsefulLink#3

Title : Atomic Theory I: The Early Days, Visionlearning Vol. CHE-1 (2),

2003.

URL :http://www.visionlearning.com/library/module_viewer.php?mid=50

Screen capture :

Description: This is an Opensource, 2003 Volume CHE-1(2) Visionlearning

material that covers the topic of Atomic Theory I : The Early Days. The site

features illustrations through appropriate links such as Simulated hydrogen and

helium atoms, which compares the two simplest atoms, hydrogen and helium.

The site also provides links to other relevant sites or modules such as Atomic

Theory II; Matter, etc.

Rationale: The learner should nd this site quite useful. The site features quizes

for registered members of Visionlearning, an alphabetical glossary of relevant

scientic terms through Visionlearning Glossary link, and an interactive practiceexercise. In addition, the learner has access to illustrations formatted for printing

on transparencies or displaying with a projector.

UsefulLink#4

Title: General Chemistry Online

URL: http://antoine.frostburg.edu/chem/senese/101/index.shtml

Screen capture :

Description: This is a General Chemistry Online resource material that links thelearner to various study material needed for this module. The range of topics that

are linkable to appropriate databases and sites include : Measurement ; Matter ;

Atoms & ions ; Compounds ; Chemical change ; The mole ; Energy and change ;

The quantum theory ; Electrons in atoms ; The periodic table ; and Chemical

bonds among other topics that are not directly relevant for this module.

Rationale: This is an invaluable resource site that has links to as many sites as

there are topics of relevance to this module. The sites are well organized with

accompanying Glossaryand Tutorial sections, just to mention two, for quick

reviews by the learner. It is site that is highly recommended to the learner as it

would make it very easy for the learner to gather relevant material. A special

feature of General Chemistry Online is the existence of a key on: common com-pounds, exam guide, features,glossary,construction kits,simulations,toolbox and


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tutorial index associated with every topic covered. This make the sites pleasant to

visit. Through the Companion Notes feature, which is available to every link, the

learner has access to material such as: learning objectives; lecture slides; lecture

notes; relevant links; frequently asked questions; etc. This makes following the

material much easier.

UsefulLink#5

Title: Atomic Structure, Bonding and Periodicity : Creative Chemistry : ASChemistry Module 1 Worksheets and Guides

URL:http://www.creative-chemistry.org.uk/alevel/module1/index.htm

Screen capture :

Description: This page provides question sheets and practical guides on atomic

structure, bonding and periodicity. The worksheets are available in PDF format

(Adobe Reader required). It is the rst part of the Advanced level (A- Level)

section on the Creative Chemistry site produced by Dr Nigel Saunders, Harrogate

Granby High School, UK. It is an Opensource material.

Rationale: The content of this page should provide the learner with good practice

questions and practical guides on the topics of atomic structure, bonding, andperiodicity. The target group here is supposed to be high school learners but the

material affords the rst year learner the opportunity to measure himself/herself

against the target group.

UsefulLink#6

Title : Lecture Help Pages with Solutions [Chemistry]

URL : http://chemistry2.csudh.edu/newlechelp/lechelpcs.html

Screen capture :

Description: Professor George Wiger from California State University, USA, has

developed these exercises and calculations. They cover: matter and measurement;

atoms and elements; molecules, ions and compounds; chemical equations and

stoichiometry; reactions in aqueous solutions; energy and chemical reactions;

atomic structures; atomic electron congurations and chemical periodicity; gases;

solutions and their behaviour; chemical kinetics; chemical equilibria; acids and

bases; and electron transfer reactions.

Rationale: This makes for a very useful resource for learners of this module.

This site links the learner to several exercises with solutions that are meant to test

his/her understanding of the numerous concepts learnt throughout this module.

The variety of the exercises makes this a worthwhile resource for the learner. Theother added advantage is the extent of coverage which takes care of virtually all

the topics or units covered in this module.


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UsefulLink#7

Title : Atoms and the periodic table.Atoms and the periodic table.

URL :http://www.chem1.com/acad/webtext/atpt/

Screen capture :

Description: Atoms and the periodic table: Introduction to the quantum theory

of the atom, atomic structure and the periodic table is A Chem1 Virtual Textbook

chapter authored by Stephen K. Lower, formerly of Simon Fraser University,Canada. The Chem1 Virtual Textbook is a collection of reference textbook

chapters and tutorial units providing in-depth coverage of topics in college-level

General Chemistry. This document covers its topic at a level appropriate for

rst-year college chemistry.

Rationale: This is a valuable 49-page pdf document that can be downloaded from

the site: http://www.chem1.com/acad/pdf/c1atoms.pdf. The document contains

important material relevant to this module. Material contained include: Quanta-

a new view of the world; The Bohr Model of the Atom; Electron congurations

of the elements; and Chemical periodicity. The last topic deals more with the

organization of the periodic table; the shell model of the atom; sizes of atoms and

ions; as well as the periodic trends in the ion formation. The learner should ndit a useful resource for a good fraction of the material needed for this module.

UsefulLink#8

Title: Chemical BondingChemical Bonding

URL :http://www.chem1.com/acad/webtext/virtualtextbook.html

Screen capture :

Description: This document is part of the Chem1 Virtual Textbook 77-page

chapter by Stephen K. Lower of Simon Fraser University, Canada that covers the

topic Chemical Bonding (http://www.chem1.com/acad/webtext/virtualtextbook.

html) and may be reproduced for non-commercial purposes only.

Rationale: Chemical bonding refers to the set of principles and theories that

govern the structure and stability of chemical substances, and thus of the re-

arrangements that occur during chemical reactions in which one substance is

transformed into another. The study of chemical bonding is thus one of the fun-

damental pillars of modern chemical science. This book chapter provides good

coverage of this very important topic that forms part of a unit in this module. The

subtopics within the book include: Bonds and molecules; Observable properties

of chemical bonds; Why do chemical bonds form; The shared-electron model

of chemical bonding; Polar and nonpolar bonds; The shapes of molecules:- the

VSEPR model; Hybrid orbitals:- the valence bond model; and the Molecular

orbital model. As much as the content may appear rather loaded, it will afford

the learner, the opportunity to read wider.


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UsefulLink#9

Title: Chemical Principles: the Quest for Insight- Second Edition

URL : http://www.whfreeman.com/chemicalprinciples/

Screen capture :

Description: This website is a book companion site for Chemical Principles:

a Quest for Insight, second edition (published by W H Freeman). This site has

been developed to serve as an additional free resource for students and instruc-tors using the textbook. Many resources to be used with this site and associated

links require Macromedia Shockwave Player (version 8.5 or above), Macromedia

Flash Player (version 6.0 or above), Apple QuickTime (5.0 or above), and Adobe

Acrobat (version 6 or above) plug-ins.

Rationale: Learners accessing this link plus associated links will nd material

contained here in very useful as they have a direct bearing on the module contents.

The material includes chapter outlines, living graphs, animations, videos, mole-

cular visualisations, simulations, exercises and links to related websites. Topics

relevant to this particular module are: atoms (the quantum world), chemical bonds,

molecular shape and structure, the properties of gases, liquids and solids, and, the

elements (the rst four and last four main groups), the d-block elements (metalsin transition). Additional topics such as thermodynamics (rst, second and third

laws), physical equilibria, chemical equilibria, acids and bases, aqueous equilibria,

electrochemistry, and chemical kinetics are beyond the scope of this module.


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UsefulLink#10

Title: Chemistrycoach.Com

URL :http://www.chemistrycoach.com/home.htm#Links

Screen capture :

..tutorialswithemphasisonapplicabilitytohighschoolchemistry

lastupdated7/04/03linksverified7/04/03

Allofthefollowingtutorialsshouldbeusefulforhighschoolchemistry

ThoseofspecialmerittoChemistry

Coachareidentifiedwitha *

..tutorials: page home 0 1 2..tutorials: page home 0 1 2 3 4 5 6 7 8 9

MathematicalSkillshaveoutgrownthispageandhavemovedtoanotherpage:Clicktogothere

ClassificationSchemes

Atomic Structure

Bonding : Ionic,

Covalent, ...

Mole

Solutions

Acids and Bases

Gas Laws

Nuclear Chemistry

Materials

Environmental

Chemistry

Electronic

Structure:

Molecular

Geometry

Stoichiometry

Solubility

Oxidation

Numbers

Liquids and Solids

Organic

Chemistry

Chemistry

Laboratory

Naming

Chemical Equation

Periodicity

Equilibrium

Oxidation-Reduction

Energy

Biochemistry

CBL

Bonding : Lewis

Dot Structures

Formulas

Groups

Kinetics

Electrochemistry

Thermodynamics

Analytical Che-

mistry

Chemistry Safety


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Description:This website links the learner to material content of virtually all

the topics covered in this module. It is an openware source for material and the

learner is encouraged to access it and its corresponding many links. The range of

topics are clearly indicated in the screen capture above and each can be accessed

individually by clicking onto them. The range of topics include: Atomic Structure,

Electronic Structure, Naming, Bonding: Lewis Dot Structures; Bonding: Ionic,

Covalent, ; Molecular Geometry; etc. Also included is a link to tutorials to

assist the learner in understanding the material covered in this module.

Rationale: This is a must-access website that will lead the learner to virtually allthe topics covered in this module. It is an openware resource that links the learner

to the relevant material covered in this module. The learner is encouraged to

access these links. Also included are links to tutorials on relevant topics covered

in this module. All the tutorials available in this website should be very useful

to material covered in high school chemistry and rst year chemistry material..

Those of special merit to Chemistry Coach are identied with a *. The website

has links to tutorials on virtually every topic covered in this module and should

prove very useful to the learner. Tutorials relevant to each topic can be accessed

via links associated with every topic. For instance, by clicking onto any of the

following, the learner is linked to the relevant site that contains the relevant tuto-

rial material: Original High School Tutorials; Relevant (High School) ChemistryResources; Chemistry Coach.


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XIV. lrig activiti

Learningactivity#1

TitleofLearningActivity:MatterandMeasurement

SpecificLearningObjectives

Dene matter, and identify and explain the differences between the various

states of matter (i.e., solids, liquids and gases).

Identify and explain the differences between physical and chemical pro-

perties of matter.

Dene and distinguish between physical and chemical changes.

Explain the differences between matter and energy.

Understand measurements and apply the International standards of measu-

rements to carry out relevant calculations associated with the particular

measurement.

Determine uncertainties and error levels in chemical experiments.

Summaryofthelearningactivity

This activity comprises two interelated study topics: Matterand measurement.

UnderMatter, you will be introduced to the three forms of matter (gas, liquid,

and solids) and the corresponding distinguishing characteristics between them at

the molecular level. A classication of material properties as extensive, intensive,

chemical, and physical properties will be made and their corresponding examples

will be given. UnderMeasurement, you will be introduced to the International

System of Measurements (SI units), which was developed to provide a very or-ganized, precise and practical system of measurements that everyone in the world

could use without ambiguity. You will be introduced to the construction of the SI

units using seven (7) base units (such as metre, kilogram, second, kelvin, mole,

ampere, and candela) from which other relevant units are derived. The last part

of this activity centres on the need to report measurements in a way that not only

shows the measurements magnitude but also reects its degree of uncertainty

since all measurements are uncertain to some degree.


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KeyConcepts

Matter: anything that takes up space and has mass.

Space: that which is occupied by matter.

Mass: a measure of a bodys resistance to a change in velocity.

Weight: refers to the force with which an object of a certain mass is attracted by

gravity to the earth or to some other body that it may be near.

Physical change: any change NOT involving a change in the substances che-

mical identity.

Chemical change: a process in which chemical bonds are broken and new ones

are made.

Physical property: anything that can be observed without changing the identity

of the substance.

Chemical property: characteristics which are exhibited as one substance is

chemically transformed into another.

Law of conservation of mass: states that mass is neither created nor destroyedin a chemical reaction.

Law of denite proportions (also called law of denite composition):

states that in a pure chemical substance, the elements are always present in denite

proportions by mass.

Listofrelevantreadings

Bishop_Book_1_ebook.pdf

Bishop_Book_2_ebook.pdf

Bishop_Book_8_ebook.pdfPhysical and Chemical Properties.htm

States of Matter.htm

Physical and Chemical Changes.htm

Reactions.htm


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Listofrelevantusefullinks

http://www.chemtutor.com/sta.htm

HTML site for material on States of Matter.

http://www.chemtutor.com/sta.htm

HTML site for material on States of Matter.

http://www.chemtutor.com/unit.htm

HTML site for material on Units, Measures and Dimensions.


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Detaileddescriptionoftheactivity

StatesofMatter:

Matter is dened as that which has mass and occupies space. Here, mass cha-

racterizes an objects resistance to change in its motion. Space, on the other hand

is that which is occupied by matter.

There are three states of matter which exist in the environment of the Earth,namely: solid, liquid, and gas. These three states of matter can be distinguished

from each other as follows:

Solid: have denite shape and denite volume;

Liquids: have indenite shape and denite volume; and

Gases: have indenite shape and indenite volume.

By denition, Indenite shape means that the sample in question takes on the

shape of the container. For instance, if water is poured from a round container

into a square container, the shape of the sample changes. On the other hand,

indenite volume means the sample would expand to ll the entire container.

Only gases do this. Thus, if you had a gas in a 5-liter container and transferred

the gas sample into a 10-liter container, the gas molecules would ll up the entire

10-liter volume. Note that in doing this, the gas becomes less dense.

Denite (for both shape and volume) means that the container makes no diffe-

rence whatsoever. If 5-liters of liquid water is poured into a 10-liter container,

the liquid would occupy 5-liters of the container and the other 5-liters would be

empty. Suppose some water was frozen in the shape of a sphere and then put

into a larger cubical shaped container. The spherical ball of ice would retain its

spherical shape as well as retaining its volume even though it had been put in a

container that was both larger and of a different shape.


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PhysicalandChemicalChanges:

PhysicalChanges

A physical change is any change NOT involving a change in the substances

chemical identity. Here are some examples:

(1) Any phase change. For instance, moving between solid, liquid and gasinvolves only the amount of energy in the sample. There is no effect on

the chemical identity of the substance. For example, water remains water,

no matter if it solid, liquid or gas.

(2) Grinding something into a powder. Or the reverse process of making a

bigger lump of stuff, say by melting lots of small pellets of copper into

one big piece.

(3) Iron (and other metals) can be made to be magnetic. This change in no

way affects the chemical identity of the element. Iron that is magnetized

rusts just as easily as iron that is not magnetized.

The terminologies used to describe some of the commonly encountered physical

changes are given below:

Change Name of changeSolid to liquid melting, fusionLiquid to gas boiling, evaporationSolid to gas sublimationGas to solid depositionGas to liquid condensation, liquefactionLiquid to solid freezing, solidication

An example of a sublimation process is conversion of dry ice from solid to gas.

It is solid carbon dioxide and goes directly from the solid state to gas in the open

atmosphere. One can make liquid carbon dioxide, but it must be done under

extremely high pressures (e.g., 5 atmospheres).


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ChemicalChanges

A chemical change means that the reacting substances(s) are changed into new

substances. The actual atoms involved remain, they are simply rearranged. The

rearrangement is called a chemical reaction. For example:

2H2O ---> 2H

2+ O

2

is a chemical reaction in which water is broken down into the hydrogen and

oxygen which make it up. Notice how the amounts of hydrogen atoms (four)

and oxygen atoms (two) do not change from one side of the arrow to the other.

However, the arrangements of the atoms is different. Some chemical bonds (the

one involved in the water) have been broken and some new chemical bonds (the

one in hydrogen and oxygen) have been formed.

A chemical change can also be dened as a process in which chemical bonds

are broken and new ones are made. Note that a process like grinding salt crys-

tals into a ne powder does not involve the breaking of chemical bonds nor the

formation of new ones, and so it is a physical change.

PhysicalandChemicalProperties

There are two types of property of matter. Physical properties describe the ma-

terial as it is. Chemical properties describe how a material reacts, with what it

reacts, the amount of heat it produces as it reacts, or any other measurable trait

that has to do with the combining power of the material. Properties might describe

a comparative trait (denser than gold) or a measured trait (17.7 g/cc), a relative

trait (17.7 specic gravity), or an entire table of measurements in a table or graph

form (the density of the material through a range of temperatures).

PhysicalProperties

Physical properties include such things as: color, brittleness, malleability, ductility,electrical conductivity, density, magnetism, hardness, atomic number, specic

heat, heat of vaporization, heat of fusion, crystalline conguration, melting

temperature, boiling temperature, heat conductivity, vapor pressure, or tendency

to dissolve in various liquids. These are only a few of the possible measurable

physical properties. A physical property of a pure substance can therefore be

dened as anything that can be observed without changing the identity of the

substance. The obervations usually consist of some type of numerical measure-

ment, although sometimes there is a more qualitative (non-numerical) description

of the property. There are many physical properties and here are some of the

more common ones:


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melting point electrical conductivity color density

boiling point thermal conductivity odour hardness

refractive index atomic radius ductility

Note that, based on similarity in physical properties, elements or compounds can

be grouped together. For instance, a group of substances can be called metals

because they all possess a set of physical properties that are similar. For example,

metals are ductile, malleable, conduct electricity and heat, and have luster. These

all reect a commonality of structure.

Note, however, that the similarities in a group do not extend to every property.

For instance, while both tantalum and sodium are metals, tantalums melting

and boiling points are 2996 C and 5425 C, respectively and Sodiums is 98 C

and 883 C, respectively. The wide disparity in the melting and boiling points

between tantalum and sodium simply highlight the wide range that exists within

the common structure that all metals have.

ChemicalProperties

This one is more difcult. There really does not exist a set of properties that

constitute chemical properties in the same way as physical properties. This is

because chemical properties are tied to the change, whereas a given substance

has a property (such as melting point) all to itself. Chemical properties include:

whether a material will react with another material, the rate of reaction with

that material, the amount of heat produced by the reaction with the material, at

what temperature it will react, in what proportion it reacts, and the valence of

elements.

Chemical properties can be dened as characteristics which are exhibited asone substance is chemically transformed into another.

Here are some examples:

(1) iron rusting. When iron (an element, symbol = Fe) rusts, it combines in a

complex fashion with oxygen to form a reddish-colored compound called

ferric oxide (formula = Fe2O

3). Not all substances rust.

(2) glucose, mixed with yeast, ferments to make alcohol. Glucose (C6H

12O

6)

is a chemical compound which enzymes in yeast can use to make ethyl

alcohol (C2H

5OH). Not all substances ferment.

(3) trinitrotoluene (TNT) reacts very, very fast when it is ignited. Among

other products, it generates plenty of nitrogen gas and of heat. Inside an

appropriate container, it can cause an explosion. Not all substances can

make an explosion.


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We can separate or purify materials based on the properties. For instance, we

can separate wheat from chaff by throwing the mix into the wind. The less

dense chaff is moved more by the wind than the denser wheat. We can separate

a mixture of sand and iron lings by magnetism. The iron lings will stick to a

magnet dragged through the mixture. We can separate ethyl alcohol (good old

drinking alcohol) from water by boiling point. This process is called distillation.

A mixture of water and insoluble material with alcohol mixed in it will release

the alcohol as vapor at the boiling point of alcohol (78 C). We can separate by

solubility. A mixture of table salt and sand can be separated by adding water. The

salt dissolves and the sand does not.

Exercise 1: What properties distinguish solids from liquids? Solids from gases?

And liquids from gases?

Exercise 2: Describe a chemical change that illustrates the law of conservation

of matter.

Exercise 3: Classify each of the following homogeneous materials as a solution,

an element or a compound: Iron, water, carbon dioxide, oxygen, glucose , blood

plasma.

Exercise 4: It is necessary to determine the density of a liquid to four signicant

gures. The volume of solution can be measured to the nearest 0.01cubic cm.

(a) What is the minimum volume of sample that can be used for the measu-

rement? Ans. 10.00 cm3.

(b) Assuming the minimum volume sample determined in (a), how accurately

must the sample be weighed (to the nearest 0.1g, 0.01g, .), if the density

of the solution is greater than 1.00g/ cm3. Ans. Nearest 0.01g.

Exercise 5: Using exponential notations, express the following quantities in terms

of SI base units:

(a) 0.13g (b) 5.23g

Exercise 6: How many signicant gures are contained in each of the followingnumbers:

(a) 113 (b) 207.033 (c) 0.0820


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Learningactivity#2

TitleofLearningActivity: AtomicStructureandPeriodicity

SpecificLearningObjectives

Explain the development of the Atomic Theory

Understand the modern atomic theory and describe the structure of the

atom.

Write electronic congurations of atoms.

Dene atomic and mass number and carry out related calculations.

Describe the thought process involved in the development of the periodic

table.

Use the periodic table to explain the structure and the properties of ele-

ments in groups and periods.

Summaryofthelearningactivity

A chemists primary interest is the behaviour of matter. However, to understand

the behaviour of matter we must rst understand its internal structure. Prior to

1897, the internal structure of the atom had been a source of speculation for thou-

sands of years. It is J.J. Thomson who discovered the electron, the rst subatomic

particle and was the rst to attempt to incorporate the electron into a structure

for the atom. Today, we know that atoms, which constitute elements, come to-

gether in different manners to form compounds and that the various manners by

which atoms combine is attributable to their individual structures, which in turn

inuences the properties of the resultant compounds. It is therefore signicant

that we have a good knowledge of the structure of this smallest building block

of an element. In this Unit, you will be expected to have a general knowledge of

the various models that have been in existence inorder to appreciate the chrono-

logy of events leading to the present modern theory or model of the atom. The

unit explains and describes the development of the atomic theory. The modern

day theory about atoms is described and details about the structure of the atom

is also included. A coverage on how to write electronic conguration of atoms;

and denitions of the various terminologies governing atomic structure and the

related calculations is made. The unit also covers the thought process involved

in the development of the periodic table. The learner will be expected to use the

periodic table to explain the structure and properties of elements in groups and

periods.


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KeyConcepts

Atom: the smallest part of an element which can take part in a chemical chan-

ge.

Atomic mass: the weighted average mass of all the atomic masses of the isotopes

of that atom.

Atomic number: counts the number of protons in an atom.

Electron: sub-atomic particles which stream from the negative electrode whenan electrical discharge passes through an attenuated gas.

Electron congurations: Lists the shells containing electrons written in order

of increasing energy.

Element: a substance which it has not yet been possible to split up into a simpler

substance, e.g., oxygen, chlorine, phosphorous, etc. It is the fundamental subs-

tance that cannot be broken down further by chemical means.

Isotopes:Atoms of the same element with the same number of protons, but

different numbers of neutrons.

Law of multiple proportions: states that, suppose that we have samples of two

different compounds formed by the same two elements. If the mass of one of

the elements is the same in the two samples, the masses of the other element are

in a ratio of small whole numbers.

Mass number:counts the number of protons and neutrons in an atom.

Periodic Law: States that all the elements in a group have the same electron

conguration in their outermost shells.

Periodic chart: is a way to arrange the elements so as to show a large amount

of information and organization.

Period: a line of elements as one reads across the periodic chart from right to

left or vice-versa.

Group (or family): a line of elements in a periodic table as one reads the chart

from top to bottom.


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Listofrelevantreadings

Atomic structure.htm

Atomic Theory I.htm

Atomic Theory II.htm

Notes Atoms & Ions.htm

Atoms & Elements.pdf

Atoms and Elements 2.pdf

Atoms and Isotopes.pdf

C1xatpt.pdf

Electron Arrangement and Periodic Law.pdf

Reviews of Elements, Compounds, and Mixtures.htm

Listofrelevantusefullinks:

http://www.chemtutor.com/struct.htm

HTML site for material on atomic structure.

http://www.chemtutor.com/elem.htm

HTML site for material on elements.

http://www.chemtutor.com/perich.htm

HTML site for material on Periodic Table.


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Detaileddescriptionoftheactivity

ModernAtomicTheory

Elements are made up of atoms, the smallest particle that has any of the proper-

ties of the element. John Dalton, in 1803, proposed a modern theory of the atom

based on the following assumptions:

1. Matter is made up of atoms that are indivisible and indestructible.2. All atoms of an element are identical.

3. Atoms of different elements have different weights and different chemical

properties.

4. Atoms of different elements combine in simple whole numbers to form

compounds.

5. Atoms cannot be created or destroyed. When a compound decomposes,

the atoms are recovered unchanged.

According to the modern atomic theory, All the matter around us is made of

atoms, and all atoms are made of only three types of subatomic particles: pro-

tons, electrons, and neutrons. Furthermore, all protons are exactly the same, all

neutrons are exactly the same, and all electrons are exactly the same. Protons and

neutrons have almost exactly the same mass. Electrons have a mass that is about

1/1835 the mass of a proton. Electrons have a unit negative charge. Protons each

have a positive charge. These charges are genuine electrical charges. Neutrons

do not have any charge.

The subatomic particles and their corresponding charges (where applicable) are

shown below:

Particle Symbol Charge RelativeMass

Electron e- 1- 0Proton p+ + 1

Neutron n 0 1

10-13 cm

electrons

protons

neutr ons

10-8 cm


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ElectronConfiguration

Protons have a positive charge and electrons have a negative charge. Free

(unattached) uncharged atoms have the same number of electrons as protons to

be electrically neutral. The protons are in the nucleus and do not change or vary

except in some nuclear reactions. The electrons are in discrete pathways or shells

around the nucleus. There is a ranking or heirarchy of the shells, usually with the

shells further from the nucleus having a higher energy as compared to those closer

to the nucleus. As we consider the electron conguration of atoms, we will be

describing theground state position of the electrons. When electrons have higher

energy, they may move up away from the nucleus into higher energy shells.

Characteristicsofelectrons

Electrons:

Are extremely small mass.

Are located outside the nucleus.

Move at extremely high speeds in a sphere.

Have specic energy levels

Electrons in atoms are arranged in discrete levels and when an electron absorbs

energy (say, when an atom is heated), it is forced to jump to a higher energy

level. This is often accompanied by emission of energy as the electron falls to

a lower energy level.

GaIn

Loss and Gain of Ene rgy

Electron levels (or sometimes known as shells) contain electrons that are similar

in energy and distance from the nucleus, with the low energy electrons being

clossest to the nucleus. We identify the electron levels by numbers 1, 2, 3, 5, 6,.... The rst shell (or energy level) 1 is lowest in energy, 2nd level is next and so

on 1


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The maximum number of electrons in any electron level is = 2n2, where n is the

shell (or energy level) number. Therefore, for:

n = 1 2(1)2 = 2

n = 2 2(2)2 = 8

n = 3 2(2)3 = 16

Order of lling electrons:

Recall that ALL electrons in the same energy level have similar energy and

that

Shell 1 2 electrons

Shell 2 8 electrons

Shell 3 18 electrons (8 rst, later 10).

Thus, the order of lling for the rst 20 electrons can be represented as:

Shell 1 2 3 4

2e 8e 8e 2e

Electron conguration lists the shells containing electrons and is written in order

of increasing energy as shown below:

Element Shell 1 2 3

He 2

C 2 4

F 2 7

Ne 2 8

Al 2 8 3

Cl 2 8 7

Periodic Law: States that all the elements in a group have the same electron

conguration in their outermost shells.

Example: Group 2

Be 2, 2

Mg 2, 8, 2

Ca 2, 2, 8, 2


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Orbital diagrams:

Orbital diagrams represent the lling and the arrangement of electrons within the

various shells of an atom. Orbital diagrams:

Use individual orbitals.

Give subshell arrangement.

Each orbital takes one electron before any other orbital in the same subshell

can receive a second electron.

Characteristics of Subshells:

Represent energy sublevels within an energy level.

All electrons in a subshell have the same energy.

The subshells are designated ass, p, d, f ..

The sublevel energies are such that: s < p < d < f.

Corresponding to each energy level, there exists various sublevels as shown

below:

Main Energy Levels Sublevels (or Subshells)

n = 4 4s, 4p, 4d, 4f

n = 3 3s, 3p, 3d

n = 2 2s, 2p

n = 1 1s

Electrons allowed:

Since all electrons in the same sublevel have the same energy, ALL 2 s electrons

have the same energy; ALL 2p electrons have the same energy which is slightly

higher than the energy of the 2 s electrons. The total number of electrons allowedin each sublevel is as shown below:

s sublevel 2 electrons

p sublevel 6 electrons

dsublevel 10 electrons

fsublevel 14 electrons


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Electron Conguration:

This is written in order of increasing energy; with superscripts giving the number

of electrons.

Example: Electron conguration of neon.

The list of subshells containing electrons is as shown in the gure be-

low:

1 s2 2 s2 2 p6

1s2

2s2

2p6

subshellMain shell

number of electrons

Writing electron congurations.

Below is a gure illustrating how to write the electron conguration of some

elements.

H 1s1

He 1s2

Li 1s2 2s1

C 1s2 2s2 2p2

S 1s2 2s2 2p6 3s2 3p4


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Example 1: The following represents the orbital diagram for a nitrogen atom:

1s 2s 2p 3s

Example 2:The orbital diagram for a uorine atom is as below:

1s 2s 2p 3s

Example 3:The orbital diagram for a magnesium atom is:

1s 2s 2p 3s

Problem 1: Write the orbital diagram for the electrons in an oxygen atom.

Problem 2: Write the orbital diagram for the electrons in an iron atom.

A diagramatic representation of thes orbitals is as below:


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A diagramatic representation of the 3p orbitals is as below:

px pz py

In general, a hydrogen atom has only one proton and one electron. The electron

of a hydrogen atom travels around the proton nucleus in a shell of a sphericalshape. The two electrons of helium, element number two, are in the same spherical

shape around the nucleus. The rst shell only has one subshell, and that subshell

has only one orbital, or pathway for electrons. Each orbital has a place for two

electrons. The spherical shape of the lone orbital in the rst energy level has

given it the name s orbital. Helium is the last element in the rst period. Being

an inert element, it indicates that that shell is full. Shell number one has only one

s subshell and alls subshells have only one orbital. Each orbital only has room

for two electrons. So the rst shell, called the K shell, has only two electrons.

Beginning with lithium, the electrons do not have room in the rst shell or energy

level. Lithium has two electrons in the rst shell and one electron in the next

shell. The rst shell lls rst and the others more or less in order as the elementsize increases up the Periodic Chart, but the sequence is not immediately obvious.

The second energy level has room for eight electrons. The second energy level

has not only ans orbital, but also ap subshell with three orbitals. Thep subshell

can contain six electrons. Thep subshell has a shape of three dumbbells at ninety

degrees to each other, each dumbbell shape being one orbital. With the s andp

subshells the second shell, the L shell, can hold a total of eight electrons. You

can see this on the periodic chart. Lithium has one electron in the outside shell,

the L shell. Beryllium has two electrons in the outside shell. Thes subshell lls

rst, so all other electrons adding to this shell go into thep subshell. Boron has

three outside electrons, carbon has four, nitrogen has ve, oxygen has six, and

uorine has seven. Neon has a full shell of eight electrons in the outside shell,the L shell, meaning the neon is an inert element, the end of the period.


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Beginning again at sodium with one electron in the outside shell, the M shell

lls itss andp subshells with eight electrons. Argon, element eighteen, has two

electrons in the K shell, eight in the L shell, and eight in the M shell. The fourth

period begins again with potassium and calcium, but there is a difference here.

After the addition of the 4s electrons and before the addition of the 4p electrons,

the sequence goes back to the third energy level to insert electrons in a dshell.

The shells or energy levels are numbered or lettered, beginning with K. So K is

one, L is two, M is three, N is four, O is ve, P is six, and Q is seven. As the s

shells can only have two electrons and the p shells can only have six electrons,the dshells can have only ten electrons and the fshells can have only fourteen

electrons. The sequence of addition of the electrons as the atomic number in-

creases is as follows with the rst number being the shell number, thes,p, d, or

fbeing the type of subshell, and the last number being the number of electrons

in the subshell.

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10 7p6

It is tempting to put an 8s2 at the end of the sequence, but we have no evidence

of an R shell. One way to know this sequence is to memorize it. There is a bit

of a pattern in it. The next way to know this sequence is to SEE IT ON THE

PERIODIC CHART. As you go from hydrogen down the chart, the Groups 1

and 2 represent the lling of ans subshell. The lling of ap subshell is shown

in Groups 3 through 8. The lling of a dsubshell is represented by the transition

elements (ten elements), and the lling of anfsubshell is shown in the lanthanide

and actinide series (fourteen elements). See gure below.

f1

- f14

P1 p2 p3 p4 p5 p6

d1d10

1 2

1


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Atoms and Elements

Elements are dened as the fundamental substances that cannot be broken down

further by chemical means. Elements are the building blocks of the universe.

They are pure substances that form the basis of all the materials around us. Some

elements can be seen in pure form, such as mercury in a thermometer; some we

see mainly in chemical combination with others, such as oxygen and hydrogen

in water. We now know of approximately 116 different elements and each of

the elements is given a name and a one- or two-letter abbreviation. Often this

abbreviation is simply the rst letter of the element; for example, hydrogen is

abbreviated as H, and oxygen as O. Sometimes an element is given a two-letter

abbreviation; for example, helium is He. When writing the abbreviation for an

element, the rst letter is always capitalized and the second letter (if there is one)

is always lowercase.

A sample of an element contains only one kind of atom in the sample. Suppose

you had a very very pure lump of copper in your hand. The ONLY type of

atom in that lump is copper, i.e., in the lump there are trillions and trillions and

trillions of copper atoms. NOTHING else. If one were to heat the lump of copper,

it would melt and eventually vaporize. The smallest unit of the copper, called

the atom, would remain unaffected by this. The atoms of copper would be in thesolid state, the liquid state or the gaseous state, but they would be EXACTLY the

same in each state. Thus, an atom could be viewed as the smallest subdivision

of an element which still retains the properties of that element. In fact, a very

good denition of an atom is: the smallest part of an element that can enter into

a chemical combination.

An atom is the single unit of an element. It is the most basic unit of the matter

that makes up everything in the world around us. Each atom retains all of the

chemical and physical properties of its parent element. The atom however, has

smaller particles called protons, neutrons, and electrons arranged in its structure.

Atoms are electrically neutral because the number of protons (+ charges) is equal

to the number of electrons (- charges) and thus the two cancel out. As the atomgets larger, the number of protons increases, and so does the number of electrons

(in the neutral state of the atom).

All atoms of an element have the same number of protons. Atoms of different

elements are distinguished from each other by their number of protons (the

number of protons is constant for all atoms of a single element; the number of

neutrons and electrons can vary under some circumstances). In order to identify

this important characteristic of atoms, the term atomic number, Z, is used to

describe the number of protons in an atom. For instance, Z = 1 for hydrogen

and Z = 2 for helium.

Another important characteristic of an atom is its weight oratomic mass. The

weight of an atom is roughly determined by the total number ofprotons and

neutrons in the atom. While protons and neutrons are about the same size, the


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electron is more than 1,800 times smaller than the two. Thus the electrons weight

is inconsequential in determining the weight of an atom. A count of the number

of protons and neutrons in an atom is also referred to as the mass number.

The number of neutrons in an atom can also vary. Atoms having the same number

of protons, but different numbers of neutrons are known as isotopes. Isotopes are

essentially atoms of the same element (since they have the same atomic number)

but having different mass numbers. For example, normally hydrogen contains no

neutrons. However, an isotope of hydrogen does exist that contains one neutron

(commonly called deuterium). Thus, the atomic number (Z) is the same in bothisotopes; however the atomic mass increases by one in deuterium as the atom

is made heavier by the extra neutron. Another example includes the isotopes of

chlorine which are chlrorine - 35 and chlorine - 37.

The Periodic Chart of the Elements

The Periodic Chart of the Elements is primarily a way to arrange the elements

so as to show a large amount of information and organization. As you read across

the chart from right to left, a line of elements is a Period whereas as one reads

down the chart from top to bottom, a line of elements is a Group orFamily. The

elements are numbered beginning with hydrogen, number one, in integers up tothe largest number. The integer number in the box with the element symbol is

the atomic number of the element which also represents the number ofprotons

in each atom of the element.

The Periodic Chart is based on the properties of matter (seeProperties of Matter

in Unit 1), where aproperty may be dened as a quality or trait or characteristic.

It is often possible to describe, identify, separate, and classify matter through its

properties. For instance, it is possible to pick out a person from a small crowd

of people based on a description (As long as the description is not too inaccu-

rate, too vague, or too biased.). In a similar fashion, one can collect a number of

properties to describe an element or compound. The properties of the element

or compound, though, are true for any amount of the material anywhere, suchthat a South African diamond is indistinguishable from an Angolan diamond by

its properties.

Periodic Properties

The periodic chart came about from the idea that we could arrange the elements,

originally by atomic weight, in a scheme that would show similarity among

groups. The original idea came from noticing how other elements combined

with oxygen. Oxygen combines in some way with all the elements except the

inert gases. Each atom of oxygen combines with two atoms of any element in

Group 1, the elements in the row below lithium. Each atom of oxygen com-bines one-to-one with any element in Group 2, the elements in the row below


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beryllium. From here as we investigate the groups from left to right across the

Periodic Chart, the story is not quite so clear, but the pattern is there. Group 3 is

the group below boron. All of these elements combine with oxygen at the ratio

of one-and-a- half to one oxygen. Group 4, beginning with carbon, combines

two to one with oxygen. The group of transition elements (numbers 21-30 and

39-48 and 71-80 and 103 up) have never been adequately placed into the original

scheme relating to oxygen. The transition elements vary in the ways they can

attach to oxygen, but in a manner that is not so readily apparent by the simple

scheme. Gallium, element number thirty-one, is the crowning glory of the Pe-

riodic Chart as rst proposed by Mendeleev. Dmitri Ivanovich Mendeleev rst

proposed the idea that the elements could be arranged in a periodic fashion. He

left a space for gallium below aluminum, naming it eka- aluminum, and predic-

ting the properties of gallium fairly closely. The element was found some years

later just as Mendeleev had predicted. Mendeleev also accurately predicted the

properties of other elements.

Most Periodic Charts have two rows of fourteen elements below the main body

of the chart. These two rows, the Lanthanides and Actinides really should be in

the chart from numbers 57 - 70 and from 89 - 102. To show this, there would

have to be a gulf of fourteen element spaces between numbers 20 - 21 and num-

bers 38 - 39. This would make the chart almost twice as long as it is now. TheLanthanides belong to Period 6, and the Actinides belong to Period 7. In basic

Chemistry courses you will rarely nd much use for any of the Lanthanides or

Actinides, with the possible exception of Element #92, Uranium. No element

greater than #92 is found in nature. They are all man-made elements, if you would

like to call them that. None of the elements greater than #83 have any isotope

that is completely stable. This means that all the elements larger than bismuth

are naturally radioactive. The Lanthanide elements are so rare that you are not

likely to run across them in most beginning chemistry classes. Another oddity

of the Periodic Chart is that hydrogen does not really belong to Group I -- or

any other group. Despite being over seventy percent of the atoms in the known

universe, hydrogen is a unique element.

Symbols of Elements

For every element, there is one and only one upper case letter. There may or

may not be a lower case letter with it. When written in chemical equations, we

represent the elements by the symbol alone with no charge attached. The seven

exceptions to that are the seven elements that are in gaseous form as a diatomic

molecule, that is, two atoms of the same element attached to each other. The

list of these elements is best memorized. They are: hydrogen, nitrogen, oxygen,

uorine, chlorine, bromine, and iodine. The chemical symbols for these diatomic

gases are: H2

, N2

, O2

, F2

, Cl2

, Br2

, and I2

. Under some conditions oxygen makes a

triatomic molecule, ozone, O3. Ozone is not stable, so the oxygen atoms rearrange

themselves into the more stable diatomic form.


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In determining the symbols of elements in the periodic chart:

Use 1 or 2 letter(s) abbreviations.

Capitalize the rst letter only

Examples:

C carbon Co Cobalt O Oxygen Mg magnesium

N nitrogen Ca calcium

F uorine Br bromine

The symbols were derived from Latin names as shown in table below:

Element Symbol Latin name

Copper Cu cuprum

Gold Au aurum

Lead Pb plumbum

Mercury Hg hydrargyrum

Potassium K kaliumSilver Ag argentum

Sodium Na natrium

Tin Sn stannum

Note: For better learning, it is recommended that a few short lists be well learned

for immediate recognition. These include: the diatomic gases (hydrogen, nitrogen,

oxygen, uorine, chlorine, bromine, and iodine), the Group one elements (lithium,

sodium, potassium, rubidium, cesium, and francium), the Group two elements

(beryllium, magnesium, calcium, strontium, barium, and radium), Group seven

elements, the halogens, (uorine, chlorine, bromine, iodine, and astatine), and the

noble gases (helium, neon, argon, krypton, xenon, and radon). If nothing else,

learning these as a litany will help you distinguish bet

yusuf chemistry

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